The primary goal of these studies is to determine the interactions among the elements of idiotype-anti-idiotype (antigen receptor-anti-receptor) networks in the regulation of immune responses and to assess the interactions of different idiotypic networks specific for the same hapten. Specific Aims are: (1) to extend studies characterizing the antibodies of BALB/c mice to the p-azophenylarsonate (Ar) hapten bearing a cross-reactive idiotype (CRIC) unrelated to the well-described CRI of A/J mice (CRIA). Structural analysis of CRIC will be accomplished by serological studies of idiotype in serum antibodies and of idiotype-bearing hybridoma antibodies, and by amino acid sequence analysis of CRIC(+) hybridoma antibodies. (2) To estimate the extent of the regulatory repertoire of anti-idiotypic specificities directed toward CRIC by studying numerous anti-idiotype-specific hybridomas. (3) To analyze the detailed cellular requirements for the induction of idiotype-specific suppressor T cells using viable CRIC-conjugated lymphoid cells as models for idiotype-bearing inducer cells. (4) To evaluate the contribution of Ig-light chain variable regions (VL) in the induction of idiotype-specific suppression of CRIC(+) antibodies by studying a mouse strain that expresses the necessary Ig heavy chains (VH) but fails to express the necessary VL required for CRIC expression. (5) To determine the interactions among idiotypic immunoregulatory networks by analyzing simulataneously the expression of two major cross-reactive idiotypes, both specific for the Ar hapten, the CRIA OF A/J and the CRIC of BALB/c in F1(BALB/c x A/J) mice. (6) To extend studies analyzing the mechanisms of clonal dominance wherein antibodies of primed B cells are prererentially expressed to the exclusion of previously unstimulated B-cell clones. Clonal expression of normal and antigen-primed lymphocytes will be monitored in cells that have been transferred into immunoglobulin (Ig) allotype congenic mice using assays for Ig allotypic markers. (7) To prepare isologous anti-anti-idiotypes to monclonal anti-CRIC and analyze their specificities and biological functions.